Notes Are Being Cut Off (Setup)

Question:

I am trying to play a KB3 program along with other programs in a Setup and notes keep dropping out. What is going on?

Answer:

KB3 programs are completely different in their synth architecture (using modeling vs sampling technology), and most consume approx. 40 of the 48 available voices (discussed at length in the K2500 KB3 Mode Addendum Manual -and- in the K2600 Performance Guide pg. 6-4). So by merely selecting a KB3 sound on the KB3 Channel (Master Mode) you are instantly activating around 40 (sometimes more) voices, and that is even without you pressing a key. (This is actually how real B3's function, as they use mechanical tone wheels that are in constant motion. To model a true B3 accurately, this behavior is simulated via KB3 oscillators "running" constantly). As you can see, however, this can potentially leave you with few voices to play any other sounds with. As a comaprison to regular (non-KB3) K25/26 programs, voices only start when you play a note.

TIP: you can see this in action if you go to the Voices display (Master mode Util page) while a KB3 program is selected. You'll see that a number of the K2's voices are active, even when no notes are being played.

The amount of polyphony allocated in a KB3 program is determine by the number of Tone Wheels in use, governed by the "NumToneWheels" parameter (on the TONEWL page in the KB3 program editor).

This parameter lets you specify the number of tone wheels used by a KB3 program (max 95) . The classic tone wheel organs used 91 tone wheels, though the lowest 12 were for the pedals only. Therefore, you may find 79 a good number of tone wheels to specify for realistic organ emulations. For every 2 tonewheels, 1 voice of polyphony is used. Therefore a 79 tonewheel program will use 40 voices: (79/2) = 39.5, which is rounded up to 40. So for "normal" multitimbral performance, this would leave you only eight voices for other programs. Beyond those "leftover" 8, dropout will occur.

Of course, you can edit the programs to lower the number of tone wheels and thereby decrease the system load and increase your leftover polyphony. As you lower the number of tone wheels, you will find that the upper part of the keyboard will "wrap" back to a lower octave in exactly the same manner as found on a real B3. The lower the number of tonewheels, the sooner it wraps.

It is important to note that KB3 programs can only be played on a single MIDI Channel. The channel selected with the KB3 Channel parameter ("Drum Channel" in K25 models) on the Master page is the channel used for KB3 programs. The default is channel 1.

It is equally important to remember that if a KB3 program is called up on the channel, the voices are being used, whether or not you have assigned that program to a track in your sequence or are currently playing it.

If you are just trying to use a KB3 organ with a bass sound in a traditional split, all of this will not be an issue as most bass-lines only consume one voice at a time anyway, but if you are hoping to layer a KB3 organ with other sounds equally polyphonic (i.e. piano, ep, strings etc) or even hope to play polyphonic programs on other channels at the same time, you will be very limited (again, typically left with around 8 voices).

In those scenarios, you are better to either :

use one of the non-KB3 organs on board (i.e. a sample-based organ program)

- OR -

use external modules / keyboards to make up the other non-organ setup zones/sequencer tracks.

Special Note for K2500 Users: a second possible explanation for premature polyphony issues: In version 2.13 of the operating system, there was a problem with stereo samples which would cause voice stealing even when there were plenty of voices available. This problem has been fixed since v2.31, so the solution in this case is to update your K2500 to the current OS.